In the field of horology and jewelry, it is conventional to produce multi-level exterior elements using photolithography and electrodeposition techniques. EP Patent 2316056 B1 notably describes a method for fabrication of a multi-level element made of metal or metal alloy, using the UV-LIGA technique. This method includes the following steps:                taking a substrate having a conductive surface        coating the conductive surface of the substrate with a first layer of photosensitive resin        irradiating the first layer of photosensitive resin through a mask corresponding to a desired pattern        developing the first photosensitive resin layer so as to create apertures therein and thereby obtain a first level of a resin mould, the apertures in the first resin layer revealing the conductive surface of the substrate        depositing another photosensitive resin layer on the developed resin layer, so as to coat the latter and, preferably, fill the apertures therein        irradiating the new photosensitive resin layer through a mask corresponding to the desired pattern        developing the new photosensitive resin layer so as to create apertures therein and to obtain a multi-level resin mould, the apertures in the multi-level mould revealing the conductive surface of the substrate        filling the apertures in the multi-level resin mould with a metal or with an alloy, by electrodeposition        removing the resin layers to reveal a multi-level metal or alloy element formed by said metal or alloy deposited in the apertures.        
The multi-level elements thus fabricated are then separated from the substrate and mounted on the body of a timepiece or piece of jewelry.
This method for fabrication of pieces provided with multi-level exterior elements has the drawback of being time consuming to implement, especially because it is necessary to completely fill the mould apertures during the electrodeposition. A second drawback is the need to assemble the exterior elements on the piece body, resulting in a risk of detachment in the event of shocks, for example.